PROJECT SUMMARY/ABSTRACT This proposal is in response to NHLBI Topics of Interest: HL-132 Advancing Research in Exercise Therapy for Chronic Heart Failure (R01). This proposal aims to optimize adherence to exercise regimens in heart failure (HF), improve physical functioning and quality of life, and reduce morbidity. HF is a major public health concern, and while survival has improved over the decades the absolute mortality rate for HF remains high at approximately 50% within 5 years of initial diagnosis. Numerous studies show that regular physical activity / exercise significantly improves exercise tolerance as well as clinical outcomes in HF. Exercise as a reliable adjunctive intervention, however, remains limited due to poor short- as well as long-term adherence. This proposed study will examine the effectiveness of the Heart Exercise And Resistance Training ? Peer Lead ActivitY (HEART?PLAY) intervention to significantly sustain exercise adherence in HF patients, as compared to a more standard exercise intervention. The HEART?PLAY intervention will be adapted from previous NHLBI-funded R01 work shown to have a sustained impact on moderate physical activity in the elderly. This proposed study will adapt the intervention to be safe for HF patients, deliver the intervention in cardiology clinics, and test adherence to the program over 18 months. Clinic staff and HF patients who are appropriate role models will be trained to teach the intervention activities with trained health educators. They will then be responsible for maintaining the program in the cardiology clinics. The HEART?PLAY program and behavior change will be sustainable because of the presence of peer and staff leadership and because it employs proven strategies from social cognitive theory and ecological models including self monitoring, social support, role modeling, and relapse prevention. In contrast to exercise classes that have a fixed schedule and limited evidence for adherence, HEART-PLAY teaches patients how to accumulate meaningful physical activity across the day and provides a supportive social infrastructure to maintain motivation. In a rigorous cluster randomized controlled trial at cardiology clinics at the University of California, San Diego (UCSD) hospitals and at the VA San Diego Healthcare System (VASDHS), we will develop and assess the HEART?PLAY intervention program in 264 socioeconomically and ethnically diverse women and men 60+ years old with either HF with preserved Ejection Fraction (HFpEF) or HF with reduced Ejection Fraction (HFrEF). Participants in the HEART?PLAY and in the STANDARD exercise programs will receive self-monitoring tools for aerobic plus resistance training as well as group education and materials. Participants in HEART?PLAY will additionally receive peer and staff leadership. We will demonstrate that the peer-led HEART?PLAY program based in the clinic setting will significantly enhance the primary study endpoint of adherence to 150 min/week of moderate physical activity/week over an 18-month follow up. We envision the study?s findings will provide a successful intervention model that will be exportable to the clinic environment.!